Steering mechanism



R853. 25 193% A, NEVEU 2&32346 STEERING MECHANISM Filed Sept. 26, 1953 2 Sheets-Sheet l INVENTOR ANSELME NEVEU A TTORNEY Reiterates? Feb.

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STEERENG li/EJECHANZSM Application September 26, 1933, Serial No. 691,014 in France May 12, 1933 1 Claim.

This invention relates to steering mechanism for automobile or like vehicles of the kind in which the movement of the steering gear connected to the wheels of the vehicle is arranged to be effected by a servo device operated by fluid under pressure under the control of: the steering wheel, and has for its object to provide an improved construction of steering mechanism of this character.

The invention utilizes the lost motion between the steering wheel or steering column and the steering gear to effect the adjustment of valve mechanism controlling communication between the servo device and a source of fluid under pressure or vacuum, and according to the principal feature of the invention this valve mechanism comprises two relatively movable and cooperating valve members, one of which is operated by the steering wheel or steering column and the other being operated by the steering gear preferably through a nut and screw.transmission.

The invention is illustrated by way of example in the accompanying drawings of which Figure 1 is a View showing the general arrangement of a form of steering mechanism embodying the invention, Figure 2 being a sectional View on an enlarged scale of the valve mechanism and its associated elements. Figure 3 is a view of a portion of the valve mechanism of Figure 2 showing the relative position of the parts during the steering operation.

Referring now to the drawings, it will be seen that the front portion of an automobile vehicle is illustrated in Figure l as provided with the usual steering wheel l mounted upon the upper end of a steering column 2, the lower end of which is connected through the usual gearing to a lever 3 which in turn is pivotally connected through a rod to the axle mounting of the front wheels 5 of the vehicle.

An intermediate point in the lever 35 is pivotally connected to the piston rod 5 of the servo device which comprises a piston 1 adapted to reciprocate in a cylinder 8. The opposite ends of the cylinder B are connected by means of pipes 9, it] re-- spectively to the passages ll, #2 in the control valve device l3. The valve device it comprises a stationary valve seat member it provided with an annular cavity 95 in open communication with the passage ii and an annular cavity it in open communication with the passagel2, together with a central port ll open to the atmosphere. An upper valve member l8 cooperates with the valve seat of the member it; and is provided with ports to, ill adapted to register with the cavities it and I6, respectively, the ports i9, opening into annular cavities El, 22, respectively, formed in the upper face of the valve member IS. A central port 23 in the valve member l8 is in permanent communication with the central port ii in the valve seat M.

Cooperating with the lower face of the valve member I8 is a lower valve member 24 provided with'central cavity 25 in open communication with the port 23, ports 26 and 21 adapted to register with the ports 20, I 9, respectively, in the upper valve member l8 and two ports, one of which is indicated at 2B ln-Figure 3 communicating with the cavity 25 and adapted to register. respectively with the ports i9, 20 in the valve member iii.

The valve member I8 is arranged to be operated by means of one or more studs or pins 29 secured to or formed integral with the valve member l8 and passing freely through suitable openings 30 in the lower valve member 2 3, the lower end of the studs 29 being secured to a rotatable spindle 3! which is operatively connected to a spindle 32 having a screw thread of relatively steep pitch formed thereon. The spindle 32 is mounted in suitable ball bearings 33 in a frame 34 provided with longitudinal slots 35, the upper end of the frame 35 being secured to the body of the valve device 13 which is mounted upon the frame of the vehicle by means of a suitable bracket 35.

An internally screw-threaded nut member 35 cooperates with the spindle 32 and is provided with trunnions or pivot pins 3! adapted to slide in the slots 35, the trunnions 31 being operatively connected by means of links 38 to a lever 39 which is mechanically connected to the lever 3.

A short tubular shaft or sleeve 40 is rotatably mounted upon the shaft 3i and is carried in a suitable bearing in the body of the valve device l3, the lower end of the shaft 10 carrying rigidly secured thereto a gear wheel il adapted to intermesh with a gear wheel 62 mounted on the steering column The shaft ill is arranged to operate the lower valve member 24 by means of one or more studs d3 secured to or formed integral with this valve member.

The upper ends of the'shafts 3| and 40 are located in a chamber t l formed in the body of the valve device it below the valve member 24, the chamber l -l being supplied with fluid under pressure through passage and pipe 46 leading to a suitable reservoir (not shown). Leakage of fluid from the chamber M past the shafts 3| and 40 is prevented by the provision of suitable packings ll.

2 acces es The operation of the mechanism is as follows:

So long as the driver of the vehicle maintains the steering wheel i and steering column 2' stationary in any angular position the parts of the mechanism occupy the position shown in Figure 2 in which fluid under pressure is supplied from the chamber i i to the left hand end of the cylinder 3 of the servo device by way of port 2? in the lower valve member 26, port it in the upper valve member 18, cavities 2i and i5, passage i i and pipe 9. Fluid under pressure is at the same time supplied to the right hand end of the cylinder 8 by way-of port 26 in the lower valve mem ber 25, port 26 in the upper valve member l8, cavities 22 and i6, passage l2 and pipe ill.

Both ends of the cylinder 8 are thus supplied simultaneously with fluid under pressure and the piston l is thus held stationary and maintains the wheels 5 of the vehicle in the position to which they have been set by the steering wheel i.

If now the driver of the vehicle rotates the steering wheel i in a counter-clockwise direction in order to turn to the left, the gear wheel 52 will be correspondingly rotated and will cause the gear wheel ii to rotate in a clockwise direction. The lower valve member 2% will accordingly be rotated to the position shown in Figure 3 in which fluid under pressure from the chamber at is still supplied to the right hand end of the cylinder t by way of ports 26 and 20 through passage [12 and pipe It. The left hand end of the cylinder 8 is however put into communication with the atmosphere by way of pipe 9, passage ll, cavities 2i and i5, and ports i9, 28, cavity 25 and ports 23 and ll.

The piston l is accordingly moved towards the left by the pressure in the right hand end of the cylinder 8 and the piston rod 6 by means of the lever} and rod d effects the displacement towards the left of the wheels 5.

The movement of the lever 3 efiects a correspending movement of the lever 39 and an up ward movement of the links 38 and of the nut member 36 connected thereto. This movement of the member 36 causes a corresponding rotational movement of the spindle 32 which is transmitted through the shaft 3i to the upper valve member l8. The latter is consequently rotated so as to restore the valve member l8 to its original position relative to the lower valve member t l shown in Figure 2 in which the left hand end of the cylinder 8 is again supplied with fluid under pressure as above described.

A similar action is evidently effected when the steering wheel i is rotated in a clockwise direc tion to cause the wheels 5 to be displaced towards the right, the movement of the lower valve member 26 relative to the upper valve member it causing the right hand end of the cylinder g to be vented to the atmosphere, until the original relative position of the valve members iii and 2 3 is restored by the actual displacement of the wheels 5.

It will thus be evident that the initial movement of the steering wheel 8 corresponding to the lost motion between the steering column 2 and. the levers 3 and 39 is caused to effect a movement of the lower valve member 2A relative to the up per valve member 88 which effects the release of fluid under pressure from one or the other of the cylinder 8 of the servo device, thereby causing the latter to effect a corresponding movement of the lever 3 and the wheels 5 of the vehicle. This movement transmitted through the lever 3t and spindle 32 rotates the upper valve member it to a pcsition in which the relative position of the valve members if; and 2% is that originally obtaining before the steering wheel 5 was rotated so that fluid is again supplied to both ends of the cylinder 3.

In the event of failure of the source of supply of fluid under pressure or in the event of the servo device or its control valve device it becoming inoperative for any reason, it will be understood that the steering wheel i will directly operate the steering gear in the usual manner through the steering column 2 and the lever ii.

Furthermore in the event of either end of the cylinder 8 of the servo device being unintentionally vented to the atmosphere as for instance by the breakage of the pipes ii or it, the consequent movement of the lever 33 to the small extent per mitted by the lost motion will cause the spindle 32 to be correspondingly rotated in a direction to move the upper valve member it to a position in which fluid is vented from the opposite end of the cylinder 8. The piston i will consequently be balanced and an effective displacement of the wheels 5 will not take place.

in owes in which the servo device is adapted to be operated by vacuum, the valve mechanism above described and illustrated will evidently be modified in such a manner that the chamber it is in open communication with the atmosphere while the port il communicates with the vacuum reservoir or its equivalent. So long as the steering wheel 6 is not being rotated, therefore, both ends of the cylinder 8 will be maintained at atmospheric pressure, one end or the other being put into communica ion with the port ll during the initial movement of the steering wheel i in one direction or the other.

The invention is evidently not limited to the particular construction above described and il-. lustrated' by way of example which may be inodified in various respects without exceeding the scope of the invention.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

a power steering illechenism, the combine tion with a steering col n a steering element, fluid pressure operated motor for operating said element, of a pair of cooperating rotatable valve elements for controlling the fluid pressure on said motor, one of said valve elements being operatively connected to and rotatable by said steering column, a screw-threaded spindle rotatable to operate the other of said valve elements, a nut member engaging the screw-threads of the spindle, the pitch of the screw-threads on the spindle being such that axial movement of the nut will rotate said spindle, an arm operated by the movement of the steering element, and linlss operatively connected to said nut to an axial movement of the nut.

NEVEU, 

